TY  - JOUR
AU  - Yeung, T. T. et al
AU  - Morales, A. I.
AU  - Tain, J. L.
AU  - Alcala, G.
AU  - Algora, A.
AU  - Agramunt, J.
AU  - Orrigo, S. E. A.
AU  - Rodriguez-Garcia, D.
AU  - Tarifeño-Saldivia, A.
AU  - Victoria, J. A.
PY  - 2024
DA  - 2024//
TI  - First Exploration of Monopole-Driven Shell Evolution above the N=126 Shell Closure: New Millisecond Isomers in Tl-213 and Tl-215
T2  - Phys. Rev. Lett.
JO  - Physical Review Letters
SP  - 072501
EP  - 7pp
VL  - 133
IS  - 7
PB  - Amer Physical Soc
AB  - Isomer spectroscopy of heavy neutron-rich nuclei beyond the N = 126 closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in Tl-213 and 874(5) keV in Tl-215. The measured half-lives of 1.34(5) ms in Tl-213 and 3.0(3) ms in Tl-215 suggest spins and parities 11/2(-) with the single proton-hole configuration pi h(11/2) as leading component. They are populated via E1 transitions by the decay of higher-lying isomeric states with proposed spin and parity 17/2(+), interpreted as arising from a single pi s(1/2) proton hole coupled to the 8(+) seniority isomer in the PbA + 1 cores. The lowering of the 11/2(-) states is ascribed to an increase of the pi h(11/2) proton effective single-particle energy as the second nu g(9/2) orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the pi h(11/2) and nu g(9/2) orbitals. The new ms isomers provide the first experimental observation of shell evolution in the almost unexplored N > 126 nuclear region below doubly magic Pb-208.
SN  - 0031-9007
UR  - https://arxiv.org/abs/2401.06428
UR  - https://doi.org/10.1103/PhysRevLett.133.072501
DO  - 10.1103/PhysRevLett.133.072501
LA  - English
N1  - WOS:001308049400010
ID  - Yeung_etal2024
ER  -